In recent years, there has been increased demand for attending or conducting sports, which originally were to be practiced in the open, regardless of weather conditions, esp., without being subjected to the influence of rainy weather. It has also been demanded to extend the season for outdoor sports activities to all the year round. Thus, massive domed buildings having a roof have been constructed in urban areas.
However, a problem with such massive domes having a roof is that even when it does not rain, they remain so roofed that their indoor atmosphere is rather a drawback as compared with a roofless sports field, because the roof above gives a sense of oppression to the spectators and players inside.
In view of such a problem, retractable roofs have been devised and proposed to expose the interior of the dome to the open air.
Until now have there been typically available sports fields having two types of movable roofs, one type being a completely slidable rectangular roof and the other type being a round roof movable in the manner of a camera lens shutter.
However, although used exclusively for small sports fields such as tennis courts, both types of roofs are not still applied to large sports fields such as baseball or soccer fields. The reasons are that, when applied to large sports fields, the known retractable roofs leave something to be desired in relation to the construction and maintenance costs, the construction techniques, the structural safety and the like.
In view of the above problem, it is therefore an object of the present invention to provide a domed structure having a massive retractable roof which is inexpensive to construct and maintain and needs no special room for housing the retractable roof, and in which the retractable roof is of sufficient structural strength and safety when applied to a large sports field and is smoothly movable with an increased opening ratio.